Thread cutting device for sewing machine



' June 21, 1966 YASUKATA EGUCHI 3,256,845

THREAD CUTTING DEVICE FOR SEWING MACHINE Filed Dec. 31, 1963 INVENTOR.

United States Patent 3,256,845 THREAD CUTTING DEVICE FOR SEWIN MACHINEYasukata Eguchi, Tokyo, Japan, assignor to Janome Sewing Machine Co.,Ltd., Tokyo, Japan Filed Dec. 31, 1963, Ser. No. 334,778 Claimspriority, applicat/iprlioJapan, Jan. 10, 1963,

3 4 Claims. (Cl. 112--252) The present invention relates to a threadcutting device for a sewing machine, and more particularly to a manuallyoperated thread cutter for cutting threads in the region of the needleplate while still connected to a workpiece.

When a seam on a workpiece has been completed on a sewing machine, theworkpiece is moved back so that the upper thread is drawn through theneedle, and the lower thread is drawn out through the needleaperture inthe needle plate. It is difficult to cut the threads in this positiondirectly adjacent the workpiece when scissors are used, and threadcutting devices directly attached to the sewing machine have beenproposed. However, thread cutting devices according to the prior artserving this purpose are complicated and difficult to operate.

It is one object of the invention to provide a thread cutting device forcutting threads leading to a workpiece on a sewing machine directlyadjacent to the workpiece so that no thread is wasted.

Another object of the present invention is to provide a thread cuttingdevice of extremely simple construction which is under full control ofthe operator.

Another object of the invention is to provide a manually operated threadcutter which is normally located below the top face of the sewingmachine table and needle or throat plate, but which can be raised to ahigher position so that threads can be inserted by the operator underthe cutting edge of the cutter.

Another object of the invention is to use an edge of an opening in theneedle or throat plate as a cutting edge cooperating with the cuttingedge of a movable cutter so that the two edges cooperate in ascissor-like manner.

Another object of the invention is to cause a resilient scissor-likeengagement between a movable cutter and a cutting edge of the needle orthroat plate.

With these objects in view, the present invention relates to threadcutting device provided in a sewing machine. One embodiment of theinvention comprises a table for supporting a workpiece and formed withan opening, cutter means located in the opening and mounted for movementbetwen a higher position located above the top face of the table and alower position located below the top face; and manually operated meansconnected to the cutter means for moving the same between the positionsthereof. In this fashion, threads leading from the sewing machine to aworkpiece on the table and inserted between the top face of the tableand the cutter means in the higher position are cut when the cutter ismoved to the lower position.

The opening is formed in a needle or throat plate. The cutter meansinclude a support rod or support portion carrying at the upper endthereof a cutter with a downwardly directed slanted cutting edge whichcuts threads crossing the opening in the needle plate.

Inthe preferred embodiment of the invention, a guide members is mountedbelow the table and has a guideway extending toward the opening in theneedle plate.

The support portion of the cutting means is resiliently v urged againstthe guideway so that the cutter is resiliently urged against an edge ofthe opening in the needle plate which thus serves as a second cuttingedge cooperaing with a slanted cutting edge of the cutter in ascissor-like fashion.

The manually operated means include a linkage located below the tableand connected to the support portion of the cutter means, and a manuallyoperated handle located above the table of the sewing machine, andconnected to the linkage for moving the cutter between the higher andlower positions.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its additional objects andadvantages thereof, will be best understood from the followingdescription of specific embodiments when read in connection with theaccompanying drawings, in which:

FIG. 1 is an elevation view, partially in section, and illustrating anembodiment of the invention;

FIG. 2 is a plan view of the device illustrated in FIG. .1;-

FIG. 3 is an elevation on an enlarged scale, partially in section,illustrating a detail of FIG. 1; and

'FIG. 4 is a fragmentary side view, partially in section andillustrating the parts of the device shown in FIG. 3.

Referring now to the drawings, a conventional sewing machine 24 which isonly schematically indicated in FIGS. 1 and 2, has a table 1 providedwith a needle or throat plate 1a which is formed with the usualapertures for the feed dog and the needle. The needle plate has arectangular opening 22 in 'which a cutter 16 and the upper end of asupport rod or support portion 15 are located. As best seen in FIG. 4,support portion 15 includes upper and lower parts which extend at anobtuse angle to each other, and is provided with lateral flaps 18engaging the sides of a guide member 20 secured to the underside oftable 1. A face of support portion 15 between the upper and lower partsof the same slidingly engages a guideway 20a which is inclined at asmall angle to a vertical plane and leads to opening 22. The main partof guide member 20 is thicker than support portion '15, but an arcuaterecess 21 in guide member 20 narrows the wall portion on which guideway20a is provided and which is embraced by flaps 18. The lower end portion23 of support portion 15 is formed with a horizontal slot 17, best seenin FIG. 3 in which a pivot pin 12 secured to the free end of a lever arm13 is received for sliding movement. lever arm 13 is fixed to ahorizontal shaft 9 which is mounted for turning movement in bearingbrackets 7 and 8 secured to the underside of table 1. The other end ofthe horizontal shaft 9 carries a fixed arm 10 connected by a link 14 toan arm 5 which is secured to a vertical shaft 4 passing through table 1and carrying at the upper end thereof a manually operated handle 3.

When handle 3 is turned about shaft 4 between two positions, lever arm13 turns between the positions illustrated in solid and chain lines inFIG. 3 while pivot pin 12 slides in slot 17 in accordance with ahorizontal component of the movement. At the same time, support portion15 is moved up and down so that cutter 16 is As best seen in FIG. 2,

moved between higher and lower positions indicated in solid and chainlines in FIG. 3. Cutter 16 has a cutting edge slanted to the horizontalplane of the top face and defining an acute angle with the correspondingparallel edges of opening 22.

Due to the angular shape of support portion 15, and the inclination ofthe upper part of support portion with respect to opening 22 andguideway a, and furthermore due to the fact that the lower end 23 ofsupport portion 15 is moved by lever army 13 in a vertical plane,support portion 15 will resiliently abut guideway 20a and the edge ofopening 22 located in the top face of needle plate 2 closer to theoperator.

Consequently, cutting edge 16a of cutter 16 and edge 22a of opening 22will resiliently engage each other in a scissor-like action during thedownward movement of cutter 16.

Operation The device is normally in a position in which cutter 16 islocated below the top face of needle plate 2 so that the cutter does notinterfere with sewing operations. At the end of a sewing operation, theworkpiece is pushed back from the raised needle and short pieces ofthread are drawn from the aperture in the needle plate and through theeye of the needle until the workpiece is in a position clearing opening22.

The operator turns handle 3 in counterclockwise direction so that leverarm 13 and cutter means 15, 16 are raised to the position illustrated insolid lines in FIG. 3. The workpiece and the threads connected theretoare manipulated so that the threads are inserted between the opening 22and the slanted cutting edge 16a directly adjacent the workpiece.Thereupon, the operator turns handle 3 in clockwise direction so thatcutter 16 is lowered and cutting edge 16a crosses edge 22a of opening 22whereby the threads are cut.

The threads are cut directly adjacent the workpiece so that no thread iswasted. The thread ends of the shuttle thread and the needle thread willhave a length corresponding to the distance between the needle apertureand opening 16, and this distance is selected so that the length of themachine threads is suitable for the next following stitch formation.

Guide member 20 may be made resilient, or resiliently mounted to exertpressure on guide portions 15 to cause resilient engagement betweencutting edges 22a and 16a.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofthread cutting devices difiering from the types described above.

While the invention has been illustrated and described as embodied in amanually operated cutter movable in an opening of the needle plate of asewing machine, it is not intended to be limited to the detail shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharcteristics of the generic or specific aspects of this invention and,therefore, such adaptations should and are intended to be comprehendedwithin the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a sewing machine, in combination, a thread cutting devicecomprising a table for supporting a workpiece and including a needleplate formed with-an opening having a horizontal circumferential edge atthe top face of said needle plate; a guide member secured to theunderside of said table and having a guideway leading to said opening insaid needle plate, said guideway defining a small angle with a verticalplane passing through said opening; cutter means including a supportportion having a face sliding on said guideway and two lateral flapsfrictionally engaging the sides of said guide mem her, said cutter meansfurther having a cutter portion having a downwardly directed cuttingedge extending at an angle relative to said circumferential edge, saidsupport portion resiliently abutting said guideway and said horizontalcircumferential edge of said opening and being guided along saidguideway for movement between a higher position in which said cuttingedge is located above said horizontal circumferential edge of saidopening and a lower position in which said cutting edge is located belowsaid horizontal circumferential edge of said opening; and manuallyoperated means connected to said cutter means for moving the samebetween said positions whereby threads leading from said sewing machineto -a workpiece on said table and inserted in substantially verticaldirection between said top face of said needle plate and said cuttingedge in said higher position of said cutter are cut when said cutter ismoved to said lower position whereby said cutting edge slidingly engagessaid horizontal circumferential edge of said opening and thereby cutssaid thread.

2. A thread cutting device as set forth in claim 1 wherein said supportportion has upper and lower parts extending at an obtuse angle to eachother, said face and said flaps being located between said two parts;and

wherein said manually operated means are connected to said lower part ofsaid support portion.

3. A thread cutting device as set forth in claim 2 wherein said manuallyoperated means include a horizontal shaft mounted on the underside ofsaid table, a lever arm secured to said horizontal shaft for turningmovement in a vertical plane and having a free end pivotally connectedto the lower end of said lower part of said support portion for movingthe same in a vertical plane whereby said support portion is resilientlyurged against said guideway and said edge of said opening.

4. In a sewing machine, in combination, a thread cutting devicecomprising a table for supporting a workpiece and including a needleplate having an aperture for the passage of a needle and of threads, andan opening having a straight sharp edge in the top face of said needleplate; a guide member secured to the underside of said table and havinga portion located underneath said needle plate and including a guidewayextending toward said opening and being inclined at a small angle to avertical plane passing through said opening; cutter means including anupright support portion and a cutter at the upper end of said supportportion, said support portion having upper and lower parts extending atan obtuse angle to each other, the upper part being inclined to thevertical, and the lower part being substantially vertical, said supportportion having a pair of lateral flaps slidingly engaging the sides ofsaid guide member and located where said upper and lower parts join sothat a face of said support portion between said upper and lower partsand said flaps slidingly engages said guideway, said upper partextending at an angle to said guideway so that said cutter resilientlyengages said sharp edge of said opening in said needle plate, saidcutter having a downwardly directed cutting edge slanted with respect tosaid edge of said opening, said cutting means being movable between ahigher position in which said cutting edge is located above said edge ofsaid opening and a lower position in which said cutting edge is locatedbelow said edge of said opening; a horizontal shaft supported on theunderside of said table; a lever arm mounted on said horizontal shaftandhaving a free end connected to said lower part of said supportportion for moving said support portion in a vertical plane whereby saidsupport portion resiliently engages said guideway and said cutterresiliently engages sai'd edge of said opening; a handle located abovesaid table and having a shaft portion passing through said table formounting said handle for turning movement; and linkage means operativelyconnecting said shaft portion with said lever arm so that said cutter ismoved between said higher and lower positions by operation of saidhandle whereby threads leading from said aperture in said needle plateto a workpiece on said table and inserted between said top face of theneedle plate and said cutting edge in said higher position of saidcutter are cut when said cutter is moved to said lower position.

References Cited by the Examiner UNITED STATES PATENTS FRANK J. COHEN,Primary Examiner.

l0 JORDAN FRANKLIN, M. J. COLITZ,.

Assistant Examiners.

